Driver for dimpling mandrels



Hg 9 H49 H. R. FlscHER DRIVER FOR DIMPLING MANDRELS Original Filed April 4, 1944 *wat HNVENT ATTQRNEY Patented Aug. 9, 1949 DRIVER FOR DIMPLING MANDRELS Howard R. Fischer, Detroit, Mich., assignor to Chicago Pneumatic Tool Company, New York, N. Y., a corporation of New Jersey Original application April 4, 1944, Serial No.

Divided and this application March 15, 1945, Serial No. 582,955

2 Claims. (Cl. 81-128) rThis invention relates to the dimpling of metal sheets around rivet holes therein in order to adapt the latter for receiving a countersunk or flush type rivet by utilizing a draw pin or mandrel when connected to a powered dimpling tool for drawing a pair of dimpling dies together upon said sheets to dimple them. The invention refers particularly to a rotatable mandrel inserting tool for speedily inserting the mandrel into one of the two dimpling dies preparatory to dimpling the metal sheets by said dimpling tool and also for quickly removing said mandrel following the dimpling operation and reinserting the mandrel in the die through another rivet hole. This application is a division of applicants application Serial No. 529,479, lled April 4, 1944, which issued as Patent No. 2,455,903 on December 7, 1948, and which covers the mandrel and method of dimpling,

Flush rivets are used extensively in aircraft construction on the exposed surfaces of the metal skin which forms a cover for the fuselage, wing sections and other structural elements. The metal sheets, usually made of aluminum alloy, are mounted in place and the overlapping portions thereof are provided with registering perforations formed by drilling or punching. The sheets are dimpled around the holes to provide recesses for receiving the heads of the rivets. The resulting structure has the advantages of increased strength of the rivet joint and decreased wind resistance.

According to one method of dimpling, which is considered to be the most effective for certain types of work, a draw pin is inserted from one side of the sheets through the rivet hole and the projecting end on the other side is grasped with a power tool which applies pressure to opposed dimpling dies through the application of tensile force to the draw pin. As soon as the dimple is formed, the draw pin or mandrel is withdrawn and moved to the next hole. The cycle of operation must necessarily be repeated in rapid succession because of the thousands of holes required to be dimpled in a single airplane.

Thus it is a main object of this invention to provide facilities for speeding up the dimpling cycle as a whole by facilitating speedy initial insertion of the mandrel into the one dimpling die and also inal withdrawal of said mandrel from the latter in such efficient manner as to save time during each cycle of the operation.

Other objects and features of the invention will appear more fully in detail from the following description, due reference being had to the accompanying drawing forming part hereof, in which:

Fig. 1 is a side elevation, largely in longitudinal section, of a rotatable mandrel inserting tool made according to the present invention and embodying the principles thereof in practical form, the tool being shown in condition for receiving a mandrel in proper position therein;

Fig. 2 is a similar View of the tool with the mandrel in place and fully inserted into a dimpling die by means of said tool;

Fig. 3 is an end elevation of the tool of Figs.. 1 and 2 as seen from the left or chuck end;

Fig. 4 is a side elevation of the shank a threaded portion integral therewith and an associated plunger, the view showing the parts turned degrees about the longitudinal axis of the shank from the position of said parts in Figs. 1 to 3;

Fig. 5 is an end elevation of the same parts shown in Fig. 4 as seen from the left end in the latter View; and

Fig. 6 is a side elevation of the mandrel alone of Figs. 1 and 2 when turned or rotated 90 degrees about its longitudinal axis from the position of said views.

When the mandrel is to be inserted into a rivet hole in one or more metal sheets to be dimpled, it is usually first screwed into a holder and then passed through a dimpling die etc., as disclosed in the Patent No. 2,333,418, granted to the present applicant November 2, 1943, and thereafter individually into each of a plurality of such holes in the sheets and each time engaged by a power operated dimpling tool provided with a second dimpling die to effect dimpling about each hole. During such operation the mandrel remains in the holder which is used to shift said mandrel from one hole to the next, being a convenient means for handling the mandrel and facilitating dimpling the sheets at high efficiency.

However, frequently certain narrow spaces are encountered in or between the metal sheets in which no adequate room is found for placing the mentioned holder, and in which not even the full length of the mandrel alone can be accommodated, so that the latter must obviously be inserted into the rivet holes from the working side, that is, from the same side upon which the dimpling tool operates. As the dimpling tool forms no part of this invention, it is superfluous to describe for the above mentioned patent discloses it in detail, but in any case, the mandrel has a series of serrations upon one end portion adapted to be engaged by said dimpling tool and a thread upon the other end. n Y

With the foregoingjobje'cts innview and in order to make it feasible to dimple metal sheets rapidly, even in narrow portions of structures including them, it is proposed to insert the mandrel through the metal sheets from the 'dimpling side directly into a dimpling diezbyscrewing it into the latter when it is located on thefother side of said sheets, while using a holder or handle to shift said die from one rivet hole to the next land render the entire operation speedy -and practical, as will now be specically set `forth.

Referring again to the drawings, a mandrel inserting tool, generally indicated at is has a shank II adapted for insertion into the chuck I2 ofna hand ,drill or preferably oa Yankee type screw driver by which to rotate the tool under 'control 'at will. Theshank il is integral with the threaded portion I3 'which is oi greater diameter than that of fthe shank and which lhas van internal bore IA "into which 'a hollow shank portion! 5`of'a'm'andrel driving plunger I6 extends. An interior expansion spring Il oc cupes the bore `Il4fin member I3 and also a bore I8 in 'said plungerfa'iid actively tends to urge said plunger out of "said borefl'll. Th'edriving 'plunger has 'a cylindrical head I 9 which is 'provided 'with opposite fiat Surfaces 2'!` on two side's'at the rear thereof. Said flat 's'iirf.ces`extend intoA the open slot 22 in the threadd'er'id of member I3 which thus virtually `fo'rrris a chuck 'core or base. Relative rotation of the Yplunger with respect to the resto'f the tool andes'peoi'ally to the shank 'Il is thereby prevented., while allowing 'free a'xial movement of 'saidplungferinto 'and out oi'core member 'I3 by` tl'e 'action'f spring l1.

The front end23'o'f th'eplunger head is of coni cal forni yand vdiametiicall'y 'across the same is cut a rwedge Ashaped "slot 25 adapted'torece'ive one end of 'the mandrel, yto bedsrib/ed, 'said fend engaging against'agroup of'chuckjaws Zi'whose rear ends 26 are correspondingly,inclined to fit against theconio'al endof Vsaidli'ead.V The 'jaws are retained in mutual l'assoclation by r'rie'a'ns of a chuck`c'asin'g21, internally threaded atS 'and screwed in upon the threads 29 of core'ifnember or body vI3 against the ring y.'l'il seated against the rear'flangel 'ns'aid core member I3, the casing 2l having a pair ofY opposite flat portions 32 adapting the casingfor engagement by a'wre'n'ch to screw the same onsaid'rnember I3. The chuck casing at theforwardend ha`s a forwardlyv tapered internal wall 33'en'gaging against inclined portions 34 upon lthe exterior forward ends of the chuck 'jawsin orderto bringthe'latter together by means ofthe driving plunger I5 under the forward bias or'impulse of the jaw vclosing spring I'I when the latter isallowed toact freely upon said jaws through said plunger.

In order to open the chuck jaws and allow insertion into the chuck 'of a drawpin or mandrel, generally indicated `at '35, ajnianually shiftable sleeve 36 is slidably {rnountedexternaily on the chuck casing andrearwardly provided with an in.. wardly turned flange 3l serving asal forward'stop against the rearend 'of the chuck 'casing 2l Ito limit forward movement of said sleeve. rIhe latter has an internal thread 38 within the forward end into which the chuck cap 39 is screwed, while being preferably knurled upon the exterior thereof to improve the grip thereon (not shown) and provided with a pair of side gaps or openings AI to allow access to the at sides 32 of the chuck casing for grip-ping the latter by a wrench when assembling or disassembling the tool. The cap 3S, while having a substantially at outer face 42 is provided with a rearwardly directed frustoconical portion 63 occupying the center area of the interior of said cap around a central aperture fili in the latter and abutting the outer ends 45 of the chuck jaws which are inclined toward the chuckcasing to correspond to the inclination oi said frusto-oonical portion.

y 'Obviously, ii thesleeve 35 is seized by the hand of the 'operator as indicated at i8 in Fig. l and drawn rearwardly while the tool is held against rearward movementl (the shank II being clamped in the chuck 'I2 of the screw driver or the like), the sleeve will be caused to occupy the retracted position shown in said Fig. 1 in contrast with the normal position indicated at lll in broken lines, and the interior central 'partijen 43 wm 'force fthe jaws 25 rearwardly, and thereby Vthe driiiing plunger 'I6 'rearwardly 'against spring il. Due to the simultaneous release of tli'e jaws iro'in intimate fcontac't with the converging 'internal 'wail 33 of the chuck casing consdiient'upon'the separating or wedging Vaction of the conical portion i3 'against the inclined 'forward ends 135 'of 'the jaws inv cooperation with the simultaneous separating or wedging action of 'the Vconical face or end 23 of the plunger against the correspondingly inclined rear ends "26 of these jaws, 'the 'latter will be separated 'to a maximum limit 'position wherein 'they engage against 'the :interior cylindrical wall '48 of the casing, 'which provides adequate "spacing apart 'of the jaws for release or insertion or" afman'drel.

The mentioned mandrel is provided at one end with la regularly spaced series of ycircurn'erential serrations 49l (Fig. 6') :adapting lSaid end to be effectively'gripped andpulledstrongly by 'a power operated l` diinpli'ng tool, the 'extreme v'e'n'd having two inclined side portions "5! 'converging oui'- ciontly to formed wedge shapedend 'adaptedto fit into the 'transverse lslot 2H 'in the end'oi the plunger Ylfiead so that rotation 'of the tool as a whole byrneans'of the-:screwpdriver'or hand d'rill connected tothe shank 'il gwillfal'so'c'ause posi'- tive rotation of the'inandrel. ATh'e other` endof the mandrel is'V provided v'with a thread''adapting the latter tolb'e screwed v'into vadirnp'lingdie 53 having a concavevportion int'o'vwhich then/letal will'be 'projected dringdiinplin'g, while thesides of said die have opposite'latfportions'orlsiots/E cut therein vto 'adapt thedieforjengagement by a bifurcated'holdr yor'fhandle'' rlfiavingfan open slot 51 upon -the 'end oi 'its longer limb l53 while the shorter lirnbfBQV-onsaid handle Ahas 'a similar slot 6I."V Therhandle'may thus be tted tothe die at either end, tlfi'e'die `fittinginto the slot in the end concerned so Jtliatit may be shifted from hole to hole-as nthe kdimplirg proceeds and the mandrel'is releasedtherefrom.- L

The lchuck jaws "are provided with 'rows of teethvZ correspondinglt'o the'serr'ations' upon the mandrel. When tli'elatt'er isinsert'ed' by'il'rst retracting the'outerisleeveilpn ltlieftool"as shown inl-iig,v A1 withftheend' ofthe mandrel wedged into the vvsl'otcll ^of fthei plunger Lin siepa'.rated"condition lows the spring l'l to force the plunger forward which thereby also forces the jaws forward and together upon the serrations of the mandrel, with the result that the latter is firmly gripped in the tool ready for positive rotation therewith upon roation of the tool itself by means of the screw driver or drill to which it is attached.

If then the metal about the rivet hole yt3 in a sheet metal structure 54 is to be dimpled, the latter having a rather restricted or narrow space 165, the die 53 may be introduced into said space and supported by holder 5B with a threaded hole `te in said die registering with the hole G3 in the sheet metal, when the mandrel inserting tool above described and with the mandrel projecting therefrom may be placed opposite the rivet hole with the threaded end 52 of said mandrel initially inserted into said hole. When the screw driver or hand drill is operated to rotate the chuck and consequently the mandrel, the threaded end 52 or said mandrel will engage in the hole y[iii in said die and be quickly screwed into the latter until the slotted end 6l of the mandrel projects beyond the die. If at this stage the outer sleeve Ele is manually withdrawn again as indicated in Fig. l, opening the chuck, the tool may be withdrawn while the mandrel remains in place in the rivet hole with the die supported thereby on the other side of the sheet metal within space 65. If a power operated dimpling tool (not shown) having a concave or frusto-conical dimpling die complementary to the die 53 is then thrust in upon the mandrel and caused to engage the same and the dimpling tool operated to dimple the sheets, the latter tool may lthen be released and the tool embodying the present invention again engaged upon the mandrel for removal thereof from the dimpled rivet hole and the die within. In order to eect this result, the screw driver or hand drill etc., is of course operated to rotate in the opposite direction from that irst used to insert the mandrel into the die, and with the mandrel thus released from the die but yet held in said tool, the die is shifted within space B5 to the next hole and the mandrel again caused to engage in the die by means of the present manually rotated tool which is then again rereleased for the dimpling operation by the power operated tool.

Upon occasional breakage of the mandrel, which is likely to occur somewhere along the threaded end 52 thereof, the slotted end 61 is readily engaged by a common screw driver and the broken part removed by unscrewing the same from the die which is obviously then immediately ready for receiving a new mandrel.

As it is well known among those skilled in the art that a mechanical screw driver of the Yankee type can instantly be adjusted for righthand rotation when the handle thereof is depressed toward the work and as easily adjusted for rotation in the opposite direction under the same conditions, the adjustment for the righthand rotation will obviously be used during the screwing of the mandrel into the dimpling die before each dimpling cycle and the adjustment for the opposite direction when unscrewing said mandrel therefrom after each dimpling operation is completed.

While the mandrel inserting tool has thus far been described as a device or attachment to be inserted into the chuck of a hand drill or a mechanical screw driver to repla-ce the screw driver bit of the latter, it is self-evident that the present invention can readily be combined with, and be built in as part of, the mechanism of said mechanical screw driver, if so desired. It is equally evident that thel tool may be made wholly or in part of steel, bronze or of any other materials as conditions may suggest. A

What is claimed is:

1. A mandrel inserting tool adapted to be rotated in one direction in order to screw a threaded mandrel into a correspondingly threaded dimpling die forming one of a pair, and to be rotated in the opposite direction in order to unscrew and release the mandrel from the die, including a chuck having a hollow chuck body, an yaxially movable member projecting slidably a distance into said hollow chuck body, a spring within the latter resiliently urging said movable member out of said chuck body, a chuck casing rotated with the chuck body surrounding said movable member out of contact therewith and terminating at the free end thereof in interior tapered walls, a group of chuck jaws with one end of each abutting the end of the axially movable member and the other end of each jaw projecting through the free end of the casing, said jaws having inclined side portions engaging slidably against the interior tapered walls of the chuck casing, rigid projections upon said axially slidable member extending into corresponding slotted portions in the sides of said chuck body allowing axial movement of said axially movable member but preventing independent rotation thereof with respect to the chuck body, a manually operated member slidably mounted upon said chuck casing having a stop engaging a portion of said casing to prevent loss or excessive movement of said manually operated member in one direction, an end wall rigid with the latter pierced by an aperture aligned with the axis of the chuck, the aperture allowing insertion of a mandrel therethrough between said jaws, said end wall forming a second stop for said manually operated member to prevent excessive movement or loss of the same in the opposite direction to that controlled by the rst mentioned stop, and means upon the ends of the jaws and the corresponding portions of said end wall and said axially movable member abutting said jaws tending to separate the jaws radially when the latter are retracted toward the chuck body by manual movement of the manually operated member against the pressure of said spring.

2. An inserting tool comprising an externally threaded supporting member having a longitudinal bore and an open slot, a casing threadably mounted upon the supporting member and having a forwardly tapered inner wall, a manually shiftable member slidably mounted on the casing and having a forwardly disposed cap portion provided With a rearwardly directed frusto-conical portion with a central aperture, a plunger comprising a head and a shank, the head having'a forward conical face with slot means thereon adapted to engage a tool and a rear portion with opposite at surfaces adapted to slidably engage the slot of the supporting member, `and the shank having a longitudinal central bore opening into the bore of the supporting member, a spring disposed within the bore of the supporting member and the bore of the plunger shank adapted to constantly bias the plunger forwardly, and a plurality of jaws restrained in mutual association by the casing, each jaw having an external wall, a forward face, a rear face, and internal gripping means, the external wall being vforwardly tapered to slidably engage the tapered inner wall of the casing, the forward face being tapered rearmassa Wardy to conform to the frusta-conical portion of the shiftable member, and the rear face being tapered forwardly to conform to the conical face of the plunger, the arrangement of the members being such that upon rearward movement of the shift-,able member the jaws are moved into open position 'and the spring is compressed and upon release of the s'hiftable member thereafter the jaws are moved Vinto gripping 'position under the forward bias of the spring.

HOWARD R. FISCHER.

REFERENCES CITED The" following references are of record in 'the me of thisv patent:

Number Number 8 UNITED STATES PATENTS Name Date Leblanc Dec. 6, 1904 `Pfeifer Dec. 8, 1908 Corn May 28, 1912 Crohn Feb. 25, 1913 Smith et al June 15, 1920 Stoner Oct. 24, 1944 FOREIGN PATENTS Country Date Great Britain Jan. 3, 1908 France Mar. 2, 1922 

